Just about all of my prints have these lines at around the same heights, and I can’t figure out why. I tried changing the nozzle, changing the layer height from 0.15 to 0.12, and changing the speed from 60mm to 40mm. All of these seemed to have helped a bit, yet they remain. I was thinking maybe as the prints get to a certain height, the shaking of the bed (Prusa MK2) caused the layers to be slightly offset perhaps. Anyone have any other ideas?
I actually had a slightly different issue. Having an Ender clone of dubious provenance, I needed to let just the tiniest amount of slack into the Z-coupler so the screw wouldn’t bind and cause banding. It’s the upright extrusions that should provide lateral stability for the Z axis.